Effects of Slow-release Nitrogen Fertilizer on Yield and Nitrogen Accumulation of Summer Maize in Shajiang Black Soil Area

[Objectives] This study was conducted to verify the field application effect of slow-release nitrogen fertilizer on summer maize in Shajiang black soil area by simultaneous sowing and fertilization, and explore the application scope and nitrogen metabolism mechanism, so as to lay a foundation for fertilizer reduction and efficiency improvement. [Methods] With maize variety Beiqing 340 and sulfur-coated urea as experimental materials, five nitrogen application levels were set, namely, control (C0), slow-release nitrogen 70 kg/hm^(2) (C70), slow-release nitrogen 140 kg/hm^(2) (C140), slow-release nitrogen 210 kg/hm^(2) (C210) and slow-release nitrogen 280 kg/hm^(2) (C280). The phosphorus and potassium fertilizers were all in accordance with the unified standard. [Results] With the application rate of slow-release nitrogen increasing, the nitrogen accumulation in organs increased first and then decreased after tasseling stage of maize. In order to reduce the fertilizing amount and increase efficiency, 210 kg/hm^(2) of slow-release nitrogen fertilizer was the best fertilizing amount for summer maize in Shajiang black soil area. [Conclusions] This study provides reference for fertilizer reduction, efficiency improvement and sustainable development of summer maize in Shajiang black soil area.

Basic Soil Productivity of Spring Maize in Black Soil Under Long-Term Fertilization Based on DSSAT Model

Increasing basic farmland soil productivity has significance in reducing fertilizer application and maintaining high yield of crops. In this study, we defined that the basic soil productivity （BSP） is the production capacity of a farmland soil with its own physical and chemical properties for a specific crop season under local environment and field management. Based on 22-yr （1990-2011） long-term experimental data on black soil （Typic hapludoll） in Gongzhuling, Jilin Province, Northeast China, the decision support system for an agro-technology transfer （DSSAT）-CERES-Maize model was applied to simulate the yield by BSP of spring maize （Zea mays L.） to examine the effects of long-term fertilization on changes of BSP and explore the mechanisms of BSP increasing. Five treatments were examined： （1） no-fertilization control （control）; （2） chemical nitrogen, phosphorus, and potassium （NPK）; （3） NPK plus farmyard manure （NPKM）; （4） 1.5 time of NPKM （1.5NPKM） and （5） NPK plus straw （NPKS）. Results showed that after 22-yr fertilization, the yield by BSP of spring maize significantly increased 78.0, 101.2, and 69.4% under the NPKM, 1.5NPKM and NPKS, respectively, compared to the initial value （in 1992）, but not significant under NPK （26.9% increase） and the control （8.9% decrease）. The contribution percentage of BSP showed a significant rising trend （P〈0.05） under 1.5NPKM. The average contribution percentage of BSP among fertilizations ranged from 74.4 to 84.7%, and ranked as 1.5NPKM〉NPKM〉NPK〉NPKS, indicating that organic manure combined with chemical fertilizers （I.5NPKM and NPKM） could more effectively increase BSP compared with the inorganic fertilizer application alone （NPK） in the black soil. This study showed that soil organic matter （SOM） was the key factor among various fertility factors that could affect BSP in the black soil, and total N, total P and/or available P also played important role in BSP increasing. Compared with the chemical fertilization, a balanced chemical plus manure or straw fertilization （NPKM or NPKS） not only increased the concentrations of soil nutrient, but also improved the soil physical properties, and structure and diversity of soil microbial population, resulting in an iincrease of BSP. We recommend that a balanced chemical plus manure or straw fertilization （NPKM or NPKS） should be the fertilization practices to enhance spring maize yield and improve BSP in the black soil of Northeast China.

Bacterial Community Structure and Diversity in a Black Soil as Affected by Long-Term Fertilization

Black soil （Mollisol） is one of the main soil types in northeastern China. Biolog and polymerase chain reactiondenaturing gradient gel electrophoresis （PCR-DGGE） methods were used to examine the influence of various fertilizer combinations on the structure and function of the bacterial community in a black soil collected from Harbin, Heilongjiang Province. Biolog results showed that substrate richness and catabolic diversity of the soil bacterial community were the greatest in the chemical fertilizer and chemical fertilizer＋manure treatments. The metabolic ability of the bacterial community in the manure treatment was similar to the control. DGGE fingerprinting indicated similarity in the distribution of most 16S rDNA bands among all treatments, suggesting that microorganisms with those bands were stable and not influenced by fertilization. However, chemical fertilizer increased the diversity of soil bacterial community. Principal com- ponent analysis of Biolog and DGGE data revealed that the structure and function of the bacterial community were similar in the control and manure treatments, suggesting that the application of manure increased the soil microbial population, but had no effect on the bacterial community structure. Catabolic function was similar in the chemical fertilizer and chemical fertilizer＋manure treatments, but the composition structure of the soil microbes differed between them. The use of chemical fertilizers could result in a decline in the catabolic activity of fast-growing or eutrophic bacteria.

Impact of Long-Term Fertilization on Phosphorus Status in Black Soil

A twelve-year field trial was carried out to determine the impact of long-term fertilization on phosphorus (P) distribu- tion in the soil profile, P balance, and the transformation and availability of soil P in a black soil (Phaeozem, FAO). Under a wheat-soybean-corn rotation, during twelve years where no fertilizer was applied, crops removed 60 and 81 mg P kg-1 soil in the control and NK treatment, respectively. About one third of the P absorbed by crops was originated from organic P. Ca2-P, Cag-P, Al-P and Fe-P were the main forms of inorganic P absorbed by crops. The surplus P from fertilization remained in the 0-20 cm soil layer and increased with the application rate of P. The combined application of NP or NPK increased available P to a lesser extent than the combined application of PK. Fertilizer P had mainly transformed to the Al-P, Fe-P, Ca2-P, and Cas-P forms. By using the P budget (X), changes in total P (Y1) and available P (Y2) in soils under the current cropping system could be predicted by the equations: Y1 = 0.02 + 1.01X and Y2 = 2.08 + 0.15X.

Study on the Balanced Fertilization forCorn in Black SoilRegion

Regressive models were obtained by employing '311 B' and '3414' optimal regressive desingns through 5 year (1993～1997) field experiment,and by datum processing with computer.These models express the relationships between corn yields in high,middle and low yield areas and N,P,and K application rates in black soil.By analysis to the models,the fertilizer application rates for maximum yield and optimal yield were achieved.

Effect of Long-Term Application of Chemical Fertilizers on Microbial Biomass and Functional Diversity of a Black Soil

An experiment with seven N, P, K-fertilizer treatments, i.e., control (no fertilizer), NP, NK, PK, NPK, NP2K, and NPK2 where P2 and K2 indicate double amounts of P and K fertilizers respectively, was conducted to examine the effect of long-term continuous application of chemical fertilizers on microbial biomass and functional diversity of a black soil (Udoll in the USDA Soil Taxonomy) in Northeast China. The soil microbial biomass C ranged between 94 and 145 mg kg-1, with the NK treatment showing a lower biomass; the functional diversity of soil microbial community ranged from 4.13 to 4.25, with an increasing tendency from control to double-fertilizer treatments, and to triple-fertilizer treatments. The soil microbial biomass, and the microbial functional diversity and evenness did not show any significant differences among the different fertilizer treatments including control, suggesting that the long-term application of chemical fertilization would not result in significant changes in the microbial characteristics of the black soil.

Combined Application of Organic and Inorganic Fertilizers on Black Soil Fertility and Maize Yield

By two years （2007-2008） located fertilizer experiment, the effect of long-term combined application of organic and inorganic fertilizers on black soil fertility and crop yield was investigated in Shuangcheng City, Heilongjiang Province. The results showed that the combined application of organic and inorganic fertilizers could increase the organinc matter, alkaline nitrogen, available phosphorus and available potassium. At the same time, the increasing application of organic fertilizer could reduce the soil bulk density and improve the field moisture capacity. Field moisture capacity and organic matter of the combined application of high quantities of organic manure and inorganic fertilizers AtB5 treatment increased the fhstest, organic matter increased by 3.33 g. kg and field moisture capacity increased by 11.25% than the beginning of the experiment. Under the same fertilization, the combined application of organic and inorganic fertilizers＇ increasing production range was higher than the single chemical fertilizers＇ which was from 0.8% to 9.4%. The results showed that the combined application of organic and inorganic fertilizers could increase the nutrient contents of soil and also was the highest productivity contribution to black soil fertility. It was the best fertilization structure of increasing productivity level and improving the soil fertility.

Effect of water and fertilizer coupling optimization test on water use efficiency of rice in black soil regions

How to improve the water use efficiency of rice in black soil regions was studied. The black soil region in paddy fields was chosen as the research object. The research showed the fertilizer coupling mathematical model with N,P,K,irrigation water( W) and water use efficiency( WUE),which was set up under the condition of controlled irrigation with quadratic D- 416 optimized saturation design. The results show that the decending order of single factor' s influence on the WUE was N,K,P and W. All the interactions between N&P,N&K,N&W,K&P,P&W and K&W on the WUE were raised initially,and when reached a certain value,they began to decline. The decending order of each interaction on the WUE was K&P,K&W,N&K,N&P,P&W and N&W. When the WUE was targeted within 1. 8- 2. 5 kg / km^3,an optimized proportion plan was obtained in the 95% confidence interval,i. e. N 87. 76- 103. 32 kg / hm^2,K_2 O 52. 37- 66. 53 kg / hm^2 and P_2O_536. 80- 46. 71 kg / hm^2. Furthermore,the late tillering of the soil moisture content was 70. 07%- 72. 57% of the saturated moisture content.

EFFECT OF ELECTRIC FERTILIZER ON SOIL PROPERTIES

Electric fertilizer, i. e. exerting electric field on plants during growing season instead of chemical fertilizer, is a kind of physical fertilizer, and the third kind of fertilizer with developmental prospect after inorganic fertilizer and organic fertilizer. For the purpose of studying the changes of physical and chemical properties of soil after exerting electric field, five treatments with different applications of chemical fertilizer were arranged on the black soil in Yushu City of Jilin Province by randomized block method, and electric field was exerted on plants every ten days during the growing season. Through sample analysis the paper arrives at following conclusions: 1) Exerting electric field can make soil′s granular structure increase, bulk density decrease, moisture capacity increase, thus improving the perviousness of soil. 2) Exerting electric field can make microorganism′s number increase and activity strengthen, thus activating nutrient and increasing organic matter content. 3) Exerting electric field with 0.1A medium has the best effect. So the chemical fertilizer can be saved. Therefore, we can say that the application of electric fertilizer is favorable for decreasing chemical poison, improving soil, relaxing the contradiction between the supply and demand of chemical fertilizer, and decreasing production cost of agriculture and forestry.

冷凉区黑土有机质和玉米产量双提升技术探索及经济效益分析

为明确有机肥还田+保护性耕作措施下黑龙江省西部土壤有机质和作物产量的双提升技术效果,2021年10月,在黑龙江省西部齐齐哈尔市梅里斯区开展试验,以玉米为供试作物,设置5个处理:有机肥+深松40 cm(YS40)、秸秆留茬+深松40 cm(WS40)、有机肥+旋耕20 cm(YS20)、秸秆留茬+旋耕20 cm(WS20)、有机肥表施+免耕(YB);一个对照:秸秆留茬+免耕(CK)。结果表明:施入有机肥的处理能够提升深土层土壤肥力,在20~40 cm土层中YS20处理与CK处理相比有机质和全氮依次提升11.56 g·kg^(-1)和0.57 g·kg^(-1);40~60 cm土层中YS40处理与CK处理相比有机质和全氮依次提升2.83 g·kg^(-1)和0.28 g·kg^(-1)。土壤结构方面,在0~20 cm土层中YB处理的容重较CK降低17.5%、含水量提升35.5%,40~60 cm土层中YS40处理的容重较CK处理降低5.3%、含水量提升38.4%。有机肥与保护性耕作处理提高了玉米不同生育时期叶面积指数、叶绿素含量和干物质积累量,进而提高了玉米产量,第二年的YS40、YS20、YB处理较CK处理分别增产14.5%、18.5%、11.4%。收益分析表明,与CK处理相比,2021年YB处理和2022年YS20处理收益增加最多,分别增加5770元·hm^(-2)和5223元·hm^(-2)。综上所述,黑龙江省西部薄层黑土实施有机肥还田+保护性耕作是提升土壤有机质、有机碳储量、全氮、全氮储量、玉米产量和经济效益的有效措施。

施肥对我国黑土农田土壤微生物群落多样性影响的研究及展望

东北黑土是珍贵的土壤资源,由于长期的重用轻养,农田黑土退化问题已是一个不争的事实。施肥是保持/提高黑土农田生产力、保障作物产量的一项重要的农艺措施。本文综述了长期施用有机肥、无机肥、有机无机肥配施,以及无机肥氮(N)、磷(P)、钾(K)及其不同的组合施肥对黑土农田土壤细菌、真菌、固氮菌、反硝化细菌等微生物的数量、群落alpha多样性和beta多样性等方面影响的最新研究进展。发现研究结果因试验地点、季节气候、试验处理、目标微生物种类、甚至研究者的采样年限而不同。多数研究发现,长期施用化肥,特别是氮肥显著地降低了细菌丰度和alpha多样性指数,但对真菌丰度和alpha多样性指数影响不显著。不同施肥明显改变了黑土微生物beta多样性,但这种改变是有限的,相同施肥处理没有驱动不同试验地点土壤微生物群落结构同质化演替,表明东北黑土微生物分布具有很强的地域性。对长期施用不同的无机肥研究发现,N素较P素和K素在驱动黑土农田土壤微生物群落变化上作用更为明显。在论述长期施用有机肥改变土壤微生物群落结构的同时,也阐述了有机肥施用带来潜在的抗生素抗性基因污染的生态风险及对抗性基因的阻控措施。文章最后总结了目前施肥影响黑土农田微生物研究中存在的不足之处,并提出5点未来应加强的研究建议。

聚脲甲醛缓释肥减量深施对小麦和玉米产量及氮肥吸收率的影响

为了探究聚脲甲醛缓释肥(PF)减量深耕对小麦和玉米作物产量、氮肥利用效率以及矿质养分迁移的影响,设置对照(CK)、尿素+旋耕(OPTX)、尿素+深耕(OPTS)、PF+旋耕(PFX)和PF+深耕(PFS)5个处理,在豫南砂姜黑土小麦、玉米农田开展大区试验。结果表明,对比传统尿素(OPT)处理,PF处理小麦、玉米产量显著高于OPT处理,尤其PFS处理较OPTX处理小麦和玉米季产量分别高12%和6.4%,较OPTS处理分别高3.4%和1.8%;与产量不同,PFS处理仅显示玉米季氮肥利用率(NUE)高于OPTX和OPTS处理,而小麦季NUE甚至低于OPTS处理,这可能与PF在小麦季深耕条件下养分释放速度慢有关。对比两种耕作方式,发现PFS处理小麦季产量与PFX处理产量无显著差别,而玉米季产量显著高于PFX处理;与产量不同,PFS处理小麦季NUE显著低于PFX处理,而玉米季无显著差别,这可能与玉米季更适宜的气象条件和小麦季PF养分的后续释放有关。对比土壤铵态氮(NH_(4)^(+)-N)、硝态氮(NO_(3)^(-)-N)残留量和总氮浓度,发现作物收获后,PFS处理0~30和30~60 cm土层NH_(4)^(+)-N残留量与PFX处理无显著差异,NO_(3)^(-)-N残留量显著低于PFX处理,而总氮含量略高于PFX处理,这可能与PF处理在小麦季深耕条件下氮素未释放完全有关。总而言之,依据作物的产量和氮肥利用效率,聚脲甲醛缓释肥在深耕条件下显示出更高的产量效益和增产潜势,尤其玉米季作物吸氮量、产量和NUE有了显著提升,值得被推荐。

长期有机肥和化肥配施对黑土细菌群落特征和大豆产量的影响

有机物料还田是提高土壤微生物多样性和提升土壤质量的主要措施,但目前有机物料还田对黑土关键土壤微生物类群的影响及其与大豆产量间的关系尚未充分明确。本研究基于东北地区44年长期黑土定位试验,研究不同施肥措施与土壤理化性质、细菌群落和大豆产能间的关联特征。结果表明:与无肥(NoF)对比,单施有机肥(M)和化肥配施有机肥(CFM)处理显著增加了土壤养分含量、微生物量碳和微生物量氮含量。化肥配施秸秆(CFS)处理的土壤细菌丰富度和多样性低于单施秸秆(S),而化肥配施有机肥(CFM)处理的土壤细菌丰富度和多样性高于单施有机肥处理(M)。相比于NoF,施肥导致富营养型细菌类群(r策略)与寡营养型细菌类群(K策略)的比值增加。长期秸秆还田(S和CFS)和施用化肥(CF)增加了细菌网络复杂性,而长期添加有机肥(M和CFM)降低了网络复杂性。结构方程模型表明土壤铵态氮、碳氮比、细菌网络结构复杂性和关键类群[硝化螺旋菌属(Nitrospira)与芽单胞菌属(Gemmatimonas)]丰度与大豆产量呈显著正相关关系。有机肥配施化肥(CFM)有利于提高关键功能微生物类群丰度、群落多样性和大豆产量。

黑土区坡耕地水土保持耕作措施对土壤理化性状的影响

为探寻黑土区坡耕地不同水土保持耕作措施对土壤理化性状的影响机理,开展了田间小区试验。设置横坡耕作(TP)、垄向区田(RF)、深松(SF)、横坡耕作+垄向区田(TP-R)、横坡耕作+深松(TP-S)、垄向区田+深松(RF-S)3种水土保持耕作措施及3种组合耕作措施,并以常规顺坡耕作(CK)为对照,分析了土壤孔隙度、土壤机械组成、水稳性土壤团聚体稳定性、土壤养分含量等指标,并采用TOPSIS模型对不同水土保持耕作措施进行了综合评价,筛选了土壤稳定性强且蓄水保肥效果良好的水土保持耕作措施。结果表明:在玉米的全生育期内,深松、垄向区田、横坡耕作均能提高土壤体积含水率。TP-S处理体积含水率最大,0~40 cm土层平均体积含水率较CK处理增加29.47%;RF-S处理平均孔隙度最大,TP-S处理次之,平均孔隙度较CK处理分别增大10.68%、9.25%;TP-S处理能够显著提高土壤稳定性,其中平均质量直径(MWD)、几何平均直径(GMD)和大团聚体含量(R0.25)较CK处理分别增加12.30%、19.57%、13.97%;TP-S处理能够改善土壤机械组成,TP-S处理粗砂粒、粉粒、黏粒含量较CK处理增加15.40%、26.89%、1.90%,细砂粒含量较CK处理降低31.56%;TP-S处理IN(无机态氮)、AP(有效磷)、AK(速效钾)含量最高,较CK处理IN、AP、AK含量分别增加42.81%~55.32%、39.69%~40.68%、20.41%~25.45%。由TOPSIS模型综合评价结果可知,TP-S处理贴合度最高,土壤结构更稳定,且蓄水保肥效果更好,为适宜该地区的水土保持耕作措施。

长期施肥对黑土和棕壤团聚体稳定性的影响及驱动因素

【目的】比较长期不同施肥措施对两种典型土壤(黑土和棕壤)团聚体分布和稳定性的影响,探究影响团聚体稳定性的关键因素,为缓解土壤结构退化提供理论支撑。【方法】依托34年黑土和45年棕壤长期定位试验,选取两定位点共有的不施肥(CK)、化肥(NPK)、化肥配施有机肥(NPKM)处理,以及黑土特有的化肥配施秸秆(NPKS)处理、棕壤特有的有机肥——猪厩肥(M)处理,采集0—20 cm土层土壤样品,测定土壤化学性质,采用湿筛法对土壤团聚体进行筛分。【结果】相比于CK,NPK处理下黑土和棕壤大团聚体(>0.25 mm)比例显著降低8.6%和11.3%,团聚体平均重量直径(MWD)分别显著减少18.6%和10.7%,说明单施化肥导致黑土和棕壤团聚体稳定性显著降低;NPKM和M处理下棕壤的MWD分别显著增加44.2%和17.9%,而NPKM处理下黑土MWD未发生显著变化,但NPKS处理下黑土MWD显著提高11.8%,说明在棕壤中施用猪厩肥,黑土中秸秆还田是提高团聚体稳定性的重要措施。土壤团聚体的稳定性主要受土壤化学性质的影响。长期施用化肥(NPK)导致黑土和棕壤的pH和交换性钙、镁离子(Ca^(2+)、Mg^(2+))降低,阻碍了大团聚体的形成和稳定。施用有机物料(M、NPKM、NPKS)抑制了土壤pH的降低,提高土壤颗粒态有机碳(POC)和矿物结合态有机碳(MAOC)的含量,促进有机碳与铁铝氧化物、钙镁离子的结合,推动了黑土和棕壤颗粒的团聚过程,进而维持和提高了团聚体的稳定性。综合分析表明,影响黑土团聚体稳定的因素从大到小依次为络合态氧化铝(Al_(p))、Ca^(2+)、POC、pH、MAOC,其中黑土团聚体稳定性与Al_(p)显著负相关,与其余因素显著正相关。影响棕壤团聚体稳定性的关键因素从大到小依次为POC、络合态氧化铁(Fe_(p))、pH、Mg^(2+)、Ca^(2+)、无定形态氧化铝(Al_(o))、Al_(p)、无定形态氧化铁(Fe_(o)),其中棕壤团聚体稳定性与Al_(o)和Fe_(o)显著负相关,与其他因素显著正相关。【结论】化肥配施有机物料(猪厩肥、秸秆)可以抑制土壤酸化,通过增加土壤POC和Ca^(2+)含量,提高黑土和棕壤团聚体的稳定性,是延缓土壤结构退化的重要施肥措施。

长期施肥黑土phoD微生物群落特征及其对有机磷组分的影响

【目的】通过分析长期施肥对黑土有机磷组分和phoD微生物群落特征的影响,探究土壤有机磷组分对微生物关键群落特征的响应,为黑土磷高效利用和制定科学的施肥策略提供理论依据。【方法】依托吉林省公主岭市始于1989年的黑土长期施肥试验,选取5个施肥处理:不施肥(CK)、施氮钾肥(NK)、氮磷钾肥(NPK)、氮磷钾+秸秆(NPKS)和氮磷钾+有机肥(NPKM)。以2018年采集的0—20 cm土层的土壤样品为研究对象,采用化学连续浸提法,定量分析不同活性的有机磷组分;采用Illumina Miseq高通量测序平台和实时荧光定量(Real-time PCR)技术,定性和定量分析土壤中phoD微生物群落特征;通过相关分析及方差分解分析,综合探究phoD微生物群落组成、土壤有机磷组分与土壤性质之间的关系。【结果】(1)除NPKM处理外,各施肥处理间总有机磷含量无显著差异,但有机磷组分含量及其占总有机磷的比例差异较大。与CK相比,NK与NPKM处理均显著增加了活性有机磷(LOP)和中活性有机磷(MLOP)含量,NK处理LOP与MLOP分别增加了108.7%和27.5%;NPKM处理LOP与MLOP分别增加了446.6%和38.1%。与NPK处理相比,NPKS处理下LOP和MLOP含量显著降低了57.7%和24.0%。(2)化肥配施有机物料(NPKS、NPKM)改变了phoD微生物的群落组成,而对其多样性无显著影响。NPKS处理显著提高Pseudomonas丰度;NPKM处理显著提高Gemmatimonas的丰度。同时,NPKS处理还显著提高了phoD基因的绝对丰度和碱性磷酸酶(alkaline phosphatase,ALP)活性。(3)相关性分析表明,phoD微生物群落组成与LOP和MLOP之间有显著的关系。方差分解分析表明,对有机磷组分含量和比例变化而言,phoD微生物群落组成单独解释率分别为12.1%和10.2%,而其与ALP活性共同的解释率分别为58.5%和58.7%,与有机碳(SOC)共同的解释率分别高达67.5%和64.7%。由此可见,群落组成与土壤性质(ALP活性、SOC)共同影响有机磷组分,且影响效果优于单独指标。【结论】长期施肥改变了phoD微生物群落组成,其与ALP活性、与SOC分别共同解释有机磷组分的变化。化肥配施秸秆通过改善phoD微生物群落特征,显著提高碱性磷酸酶活性,从而促进有机磷矿化,提高黑土磷素的利用效率。

化肥有机肥配施对黑土团聚体稳定性及其富里酸结构的影响

为探讨化肥有机肥配施对黑土团聚体稳定性及其富里酸结构的影响,依托中国科学院海伦农业生态试验站2001年设置的长期定位试验,分析不施肥(CK)、单施化肥(NPK)、化肥+15000 kg·hm-2有机肥(NPKM1)及化肥+22500 kg·hm-2有机肥(NPKM2)处理对土壤团聚体稳定性、团聚体富里酸结构及光学特性的影响。结果表明:(1)化肥有机肥配施显著提高了0~40 cm土层>0.25 mm团聚体分布比例,增强了土壤团聚体稳定性;与CK相比,NPKM1和NPKM2处理的0~20 cm土层>0.25 mm团聚体分布比例分别增加6.2%~26.3%和8.4%~50.2%。(2)土壤各粒径团聚体富里酸包含类富里酸、类胡敏酸和类蛋白质共3种荧光组分,化肥有机肥配施提高了类富里酸、类胡敏酸组分荧光强度及百分比和类蛋白质组分荧光强度,降低了类蛋白质组分荧光强度百分比;与CK相比,NPKM1和NPKM2处理>0.25 mm团聚体富里酸的类富里酸和类胡敏酸组分荧光强度分别提高7.0%~30.5%和12.8%~45.4%。同时土壤各粒径团聚体富里酸均受自生源和外生源共同作用的影响(FI(荧光指数)>1.4,0.8<BIX(自生源系数)<1.0),呈现强腐殖化和新近自生源特征(3.0<HIX(腐殖化指数)<6.0)。(3)土壤各粒径团聚体富里酸的SUVA 254、SUVA 280和E 4/E 6值随有机肥施用量增加而增加,芳香性增强,分子结构变简单。相关性分析表明,土壤团聚体富里酸荧光组分、芳香性(SUVA 254)、腐殖化程度(HIX、E 4/E 6)是影响团聚体稳定性的重要因素。因此,化肥有机肥配施通过增加团聚体富里酸荧光组分强度,提高团聚体芳香性和腐殖化程度,进而提高土壤团聚体稳定性。

秸秆还田配施氮肥对黑土玉米田土壤CO_(2)排放与碳平衡的影响

为探寻不同秸秆还田方式配施氮肥对黑土玉米田土壤CO_(2)排放与碳平衡的影响,于2023年开展大田试验,设置秸秆离田(S0,对照)、秸秆覆盖还田(S1)、秸秆旋耕还田(S2)3种秸秆还田方式,同时设置常规施加氮肥(N,250kg/hm^(2))与不施加氮肥(W,0kg/hm^(2),对照)2种施氮模式,共计6个处理。测定不同处理下玉米生育期土壤CO_(2)排放通量以及玉米收获后土壤有机碳(SOC)、可溶性有机碳(DOC)、微生物量碳(MBC)含量,探究土壤CO_(2)累积排放量与SOC、DOC、MBC含量的关系,并分析黑土玉米田生态系统碳平衡状况。结果表明:各处理中土壤CO_(2)累积排放量从大到小依次为S2N、S1N、S0N、S2W、S1W、S0W,其中S2N处理土壤CO_(2)累积排放量较S0W处理显著增加70.31%(P<0.05)。在相同施氮模式下,秸秆还田能够有效增加SOC、DOC、MBC含量,且土壤CO_(2)累积排放量与SOC、DOC、MBC含量呈正相关关系。不同秸秆还田方式配施氮肥下,S1N处理玉米产量最高,为13534.4kg/hm^(2),作物碳排放速率最低,为0.122kg/kg。不同秸秆还田方式配施氮肥下黑土玉米田生态系统碳平衡值均为正值,表现为较强的碳“汇”,其中S1N处理碳平衡值和土壤固碳潜力最大,较其他处理分别增加13.12%~94.05%、3.49%~25.32%。综上所述,在本试验条件下,秸秆覆盖还田+常规施氮(S1N处理)可以实现黑土玉米田土壤固碳减排和作物增产目的。

节水灌溉下生物炭与有机肥添加对黑土区稻田净碳排放的影响

为探寻节水灌溉条件下施入生物炭与有机肥对黑土区稻田净碳排放的影响,于2023年开展田间试验。试验设置常规淹灌(F)和控制灌溉(C)两种灌溉模式,同时在每种灌溉模式下设置生物炭还田(B)和有机肥还田(O)2种物料还田形式,以及无物料还田(N)作为对照组,共计6个处理。分析了两种灌溉模式下施入生物炭与有机肥对稻田土壤CH_(4)、CO_(2)、N_(2)O排放和水稻产量的影响,并结合土壤有机碳含量的变化,计算各处理的净温室气体排放量(NGHGE)。结果表明:在施入相同物料下,控制灌溉处理CH_(4)排放总量较常规灌溉减少71.06%~85.39%;CO_(2)、N_(2)O排放总量较常规灌溉分别增加41.89%~47.97%、27.56%~38.26%。与对照处理相比,生物炭施入使稻田N_(2)O、CH_(4)排放总量分别降低14.31%~23.90%、15.10%~23.83%,CO_(2)排放总量增加23.03%~26.63%;有机肥施入使稻田N_(2)O、CH_(4)、CO_(2)排放总量分别增加8.22%~12.09%、18.36%~19.22%、51.48%~53.48%。生物炭与有机肥施入均能增加土壤有机碳储量与水稻产量,且控制灌溉下增幅效果更加明显。控制灌溉处理NGHGE均显著小于常规灌溉(P<0.05),且在控制灌溉下,与对照处理相比,施入生物炭与有机肥处理NGHGE分别减少44.01%、6.38%。综合来看,控制灌溉下施入生物炭提高了水稻产量,同时增加了土壤有机碳储量,并有效减少了黑土区稻田净碳排放。该研究结果可为东北黑土区稻田制定节水、增产、固碳减排的水碳管理策略提供科学依据,对保障东北地区可持续农业发展具有重要意义。